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Questions and Answers
Where does catabolism of protein occur?
What is the result of protein catabolism?
What is the approximate half-life of a body protein?
What is the daily total protein turnover in a healthy adult?
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What percentage of protein synthesis is used for the synthesis of N-compounds?
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Which amino acid is used to synthesize nitric oxide?
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What is the fate of absorbed amino acids?
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What percentage of protein synthesis is oxidized to provide energy?
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Where does ammonia detoxification mainly occur?
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What is the nitrogen content of urea?
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What is the result of a complete loss of enzyme in inherited diseases of the urea cycle?
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What induces the enzymes of urea synthesis?
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What is the byproduct of glutaminase action on glutamine?
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What is the purpose of the urea cycle?
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What is the result of partial loss of enzyme in inherited diseases of the urea cycle?
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What is the precursor of urea in the urea cycle?
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What is the function of transamination?
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Which enzyme is involved in the deamination of glutamate?
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What is the cofactor required for transamination reactions?
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What percentage of nitrogen in the body is found in proteins?
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What is the byproduct of deamination reactions?
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What is the term for the removal of the amino group (-NH) of an amino acid?
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What is the total amount of nitrogen in a 70kg male?
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What is the clinical characterization of ammonia toxicity?
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What is the number of essential amino acids that must be provided in the diet?
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What percentage of the amino acid pool is made up of glutamine, alanine, proline, and glycine?
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Which pathway is involved in the synthesis of amino acids with 4 and 5 carbon atoms?
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What is the result of the transamination reaction?
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Which of the following amino acids is semi-essential?
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What is the end product of the urea cycle?
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Which amino acid is converted to pyruvate during catabolism?
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What is the byproduct of the removal of the amino group from an amino acid?
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Phenylketonuria (PKU) is characterized by a deficiency of which enzyme?
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What is the primary clinical manifestation of Phenylketonuria (PKU)?
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How is Phenylketonuria (PKU) typically diagnosed?
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What is the primary function of insulin and growth hormone in the body?
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What is the building block of protein structure?
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What type of amino acids must be supplied by the diet?
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What is a potential consequence of untreated Hyperammonemia?
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Where does the synthesis of urea occur?
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What is the primary effect of Phenylketonuria (PKU) on brain development?
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Study Notes
Metabolism of Protein
- Catabolism of protein occurs in the gastrointestinal tract and involves the breakdown of peptide bonds into free amino acids by proteases and peptidases.
- The released amino acids are absorbed into the circulation and used by tissues, such as skeletal muscle, adipose tissue, and liver, with the help of insulin and growth hormone.
Dietary Proteins and Amino Acids
- Dietary proteins are digested in the stomach and intestine, releasing amino acids into the bloodstream.
- There are 20 amino acids, which are classified into essential and non-essential amino acids.
- Essential amino acids (9) must be supplied by the diet, while non-essential amino acids can be synthesized by the body.
Amino Acid Functions
- Amino acids are used for protein synthesis, N-compound synthesis, and energy production.
- They are also used for the synthesis of signaling molecules, such as nitric oxide and hydrogen sulfide.
Urea Synthesis and Ammonia Metabolism
- Urea synthesis occurs exclusively in the liver and is a vital process for removing excess nitrogen from the body.
- The urea cycle involves the conversion of ammonia to urea, which is then excreted in the urine.
- Ammonia toxicity can lead to serious clinical symptoms, including vomiting, lethargy, and mental retardation.
Regulation of Urea Synthesis
- Urea synthesis is regulated by protein diet, with high protein diets inducing the enzymes and low protein diets or starvation repressing them.
- Inherited diseases of the urea cycle can lead to hyperammonemia, which can be fatal if left untreated.
Transamination and Deamination
- Transamination involves the transfer of the amino group from one amino acid to another.
- Deamination involves the removal of the amino group from an amino acid, resulting in the release of free ammonia.
Nitrogen Metabolism
- The total amount of nitrogen in the body is approximately 2.0 kg (3% of body weight).
- Proteins are the major nitrogen-containing compounds in the body, accounting for 90% of the total nitrogen.
Amino Acid Metabolism Diseases
- Phenylketonuria (PKU) is an inherited metabolic disorder caused by a deficiency of phenylalanine hydroxylase, leading to the accumulation of phenylalanine and its toxic metabolites.
- PKU can result in abnormal brain development and intellectual disability if left untreated.
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Description
Learn about the catabolism of proteins, how they are broken down in the gastrointestinal tract, and the resulting release of free amino acids. Understand the role of protease and peptidase in this process and how amino acids are used by tissues. Test your knowledge of protein metabolism and digestion!
